Hypothermia and rewarming times during general anesthesia in Hispaniolan Amazon parrots (Amazona ventralis): A comparative study between isoflurane, sevoflurane and desflurane.

To evaluate induced hypothermia and rewarming times in Hispaniolan Amazon parrots (HAP ; Amazona ventralis) anesthetized using isoflurane, sevoflurane or desflurane, and to describe selected cardiovascular and respiratory effects. Randomized, balanced, crossover experimental study. A group of 12 adult HAP. Parrots were premedicated with intramuscular butorphanol (0.5 mg kg–1) and anesthetized with the three inhalants with a 7 day washout period between events. Anesthesia was induced using isoflurane at 4 vol%, sevoflurane at 6 vol% or desflurane 12 vol% carried in oxygen, delivered via face mask. After orotracheal intubation, anesthesia maintenance was with end-tidal concentrations of 1.4–2% (F e′ Iso), 2.4–3% (F e ′Sevo) and 8.5–9.2% (F e ′Des). Hypothermia was defined as an esophageal temperature (BT) below 37.8 °C. External heat support was provided when BT dropped to 37.5 °C. Time for temperature decrease from 38.9 °C to 37.5 °C (T1), time to first increase in BT above 37.5 °C (T2) and time from external heat support to achieving 38.9 °C (T3) were recorded and compared via Friedman tests with post hoc Dunn's test. Heart rate, respiratory rate and end-tidal carbon dioxide, amongst other variables, were evaluated. All inhalants caused hypothermia (T1): isoflurane, 12 (2–37) minutes [median (range)]; sevoflurane, 12 (4–18) minutes; desflurane, 11.5 (6–24) minutes, with no significant differences between treatments (p > 0.05). T2 was significantly (p = 0.042) longer for sevoflurane than for desflurane but not isoflurane. Transient apnea was observed with all inhalants, including 25% of birds anesthetized with sevoflurane. Second-degree atrioventricular block and ventricular escape beats occurred with all inhalants with hypothermia potentially exacerbating cardiac arrhythmias. Hypothermia rapidly developed in butorphanol-sedated HAP anesthetized using isoflurane, sevoflurane or desflurane. Sevoflurane prolonged warming time. Hypothermia may be associated with an increased likelihood of bradyarrhythmia in parrots anesthetized with inhalants. [ABSTRACT FROM AUTHOR]